Confused about fat? Here’s a crash course to help you distinguish the good from the bad.

There are three types of fat: monounsaturated, polyunsaturated and saturated. Monounsaturated fats – including olive oil, sesame oil, canola oil, almond oil, flax oil and fish oil – are good fats. These contain essential fatty acids, such as omega-3 and gamma-linolenic acid (GLA), that are critical to brain development and function, skin health, vascular health, proper immune system function, fertility and normal physical development.

Polyunsaturated fats, such as margarine, corn oil, hydrogenated safflower oil and sunflower oil, also contain essential fatty acids. Unfortunately, these fats are also highly refined and contain large amounts of trans fat. And trans fat, created by hydrogenating vegetable oil to make it spreadable, can play a role in both cancer and heart disease.

Saturated fats are the bad kind of fat and include butter, peanut oil, coconut oil, palm kernel oil and lard. These saturated fats elevate cholesterol and triglyceride levels, leading to an increased chance of heart attack and stroke. These oils are best avoided.